1. Field of the Invention
The present invention relates to an improved socket assembly for use with an integrated circuit device or package (IC), having a socket which opens with force applied on the top edges of the socket to allow insertion or removal of the IC, and in one aspect to an improved socket in that means are provided to indicate an opening of the contacts to allow insertion and/or removal of the IC.
2. Description of the Prior Art
Top loading sockets for integrated circuit devices or packages (IC's) are known and are used to connect IC's to printed circuit boards for test or burn-in by automated operations, or for the functional application affording the replacement of the IC without subjecting other components on a printed circuit board or the like to heat, to afford the removal or replacement of the IC. The sockets are designed to load and unload the IC from the top of the socket. This is done manually or by automatic machines, but in any event, the cover on the socket is forced toward the socket body and a plurality of contacts are moved against their biasing force to a retracted position allowing insertion or removal of the IC. It has become important when manual pressure is applied against the cover to know when the open position has been reached to limit the continual application of force to the cover.
Examples of the sockets or carriers of the prior art include applicant's own U.S. Pat. No. 4,993,955 disclosing a carrier for an IC device which has leads and which has a cam member inserted on the socket body to withdraw the contacts, against their inherent biasing force, from a contacting position to a retracted position upon the movement of the cover toward the socket body. There are other patents which show a top load socket having similar top load characteristics but these sockets have the cover engaging each of the plurality of contacts directly to retract the same. These patents include patents such as U.S. Pat. No. 5,076,798 which have a socket body forming a support housing, a plurality of contacts and a contact shutter member comprising a pair of push-down operation portions disposed at both outer sides of the IC receiving window or opening. Guide members are used to maintain the movement of the shutter portions in the vertical direction. This patent also illustrates the use of a pushing portion 21 on the push-down operation portions 18, which has an initial gently inclined surface 21a at a front stage pushing portion and with a steeply inclined surface 21b at a rear stage pushing portion 21b. These portions are formed as linear surfaces and engage the pressure receiving portions 11 of each of the contacts 4. This patent, however, is not considered to provide a teaching of the present invention since the teaching of this patent is to use a gently inclined surface against the contact during the initial retracting stage when the resilient displacement can be obtained by a comparatively small displacement force, and the push-down force is abruptly reduced by using the rear stage steeply inclined surface 21b on the contact 4 to perform the remaining displacement at the latter half stage where the resilient force is increased, thereby achieving a targeted displacement amount and a targeted generally uniform push-down force since the push-down force can be reduced as a whole and a required amount of backward displacement can be obtained with a limited push-down stroke.
The present invention has as its purpose the creation of a change (or step) in the retracting movement of the cover to create an audible sound and/or a sharp change in the force needed to depress the cover and to provide a sensory indication to the operator that, and when, the contacts have reached a retracted open position for reception or removal of the IC.
In the socket of the present invention, the retraction device to retract the contacting portion of the contacts restricts displacement of the contacting portion and assures positive movement of the contacting portion. Further, there is a noted change in the retraction force during the lineal movement of the cover to clearly indicate that the socket is in the open position with the contacting portions of the contacts retracted.